Exercise is good for your overall health and your heart in particular. Guidelines suggest that we should be doing 150 minutes of moderate to vigorous activity per week.
But does it matter when you do this exercise? Should you spread it out during the week or does it lose some of the benefit if it is included at the weekend?
A a new study analysis of data from UK Biobank attempted to answer this question.
About 90,000 healthy middle-aged people wore wristbands (accelerometers) that track their activity. Their activity levels were recorded for a week with particular attention being paid to moderate to vigorous activity (more on that later).
The researchers found that in the six years following the accelerometer assessment, people who did moderate to vigorous regular activity had less stroke, heart attack, heart failure and atrial fibrillation (irregular heart rhythm) compared to sedentary people.
The novel result of this study was that there was no difference in the results of those who did more than half of their activity at the weekend compared to those who spread it out during the week.
Regardless of when it was done, moderate-vigorous physical activity was associated with improved heart health.
In the study, the authors called people who did more than their 150 minutes a week of moderate to vigorous activity “weekend warriors”. This suggests Lycra-clad cyclists riding up mountains or muddy middle-aged men playing a grueling 90 minutes of football.
Over 37,000 people in the study met the definition of “hero of the week” so why aren’t the roads filled with cyclists and the fields filled with footballers? It seems to contradict the obesity epidemic and the sedentary lifestyle we hear so much about.
Weekend heroes? Seriously?
It may seem like semantics, but the definition of the “weekend hero” is important. In this study, the threshold used for moderate to vigorous exercise was three “magnitudes” (the metabolic equivalent of the task). The mets scale is used to measure physical activity.
For example, washing the dishes is 2.5 metres, vacuuming is 3.3 meters and walking at 3mph is 3.5 metres. To put this into context, cycling at 15mph on the flat is 10 metres.
The threshold of three meters is rather unambitious and it seems that many people would achieve it in their daily lives without a concerted effort to exercise.
So maybe when thinking of the people in this study instead of calling them “weekend warriors” they should be called “Saturday strollers” or “Sunday stretchers”.
The other point about this study is that these people were not sports people or athletes but ordinary middle-aged people doing their normal activities, including exercise and some of them in their normal activities measured on speedometers.
This context is important when considering how we can use these findings to inform our patients. I don’t want anyone to think that two and a half hours of vacuuming or taking a walk at the weekend is enough to prevent heart disease.
It is the bare minimum fitness level. To see real benefits, you’ll have to break a sweat.
The relationship between exercise and heart health is simple: the more you exercise, the more your health improves. This study showed that doing some physical activity is better for your heart than being sedentary, which is an important message for the many people who don’t manage 150 minutes of moderate activity a week.
Knowing these limitations of this study, we should avoid the interpretation that it is okay to live a relaxed life from Monday to Friday and then take an hour or so of walking on Saturday and Sunday.
The results of this study do not support this interpretation. If 150 minutes without breaking a sweat is all you can manage, it doesn’t matter when you do it. But if you can manage something more difficult, you should really try to do it.
The results of this study do not apply to more intense exercise, and if the opportunity to bike to work on Tuesday or go swimming on Thursday presents itself, you should take it. Your heart will thank you.